Method of controlling production of continuous filaments



Nov. 16,

F. A. MENNERICH METHOD OF CONTROLLING PRODUCTIONOF CONTINUOUS FILAMENTS Filed July 5, 1961 v mum: ADJUN 1MPER TMENT DEGREES F Big-J.

FRED A. MENNER/CH ATTORNEYS INV EN TOR.

United States Patent f METHOD OF CONTROLLING PRODUCTEON OF CONTINUOUS FILAMENTS Fred A. Mennerich, Cumberland Hill, RJL, assignor to Owens-Corning Fiherglas Corporation, a corporation of Delaware Filed July 3, 1961, Ser. No. 121,623

4 Claims. (Cl. 652) This invention relates to the production of textile strands of continuous filaments of heat-softenable materials such as glass and the like, and more particularly to a method and means for overall monitoring and fixing of dimensions of filaments produced of such materials.

In producing strands of continuous fibers or filaments of heat-softenable material such as glass, the filaments are usually drawn from streams supplied from a molten mass. One method for regulating the dimension of filaments in such strands is to periodically weigh a skein of strands cut from a package collected over a relatively short period of time as compared to a full packaging cycle. The actual weight of the skein or sample is then compared against a calculated weight for fibers of desired diameter collected over a corresponding period and then making an adjustment in the rate of flow of material in the streams such as by way of the temperature and viscosity of the molten mass, which adjustment is dependent upon deviations of the measured weight of the sample from the calculated weight for the desired filaments.

In collecting a skein of such strand, the time of collection of the sample must of necessity be known such as by actual time measurement in order to permit accurate calculation of the weight of filaments of exact desired diameter in the strand. An alternate method for taking a sample of the strand of filaments is to collect full packages of the strand over a predetermined exact period of time and then to make corresponding weight calculations and actual weight measurements in order to determine the magnitude of adjustment necessary to correct the rate of flow of the heat softened material for the desired diameter of filaments. In the latter case, the tare weight of the collection spool or tube must be known to permit measurement of the sample in the full package only. In both instances, however, compensation must be made for moisture content, such as the moisture applied to the filaments in the form of sizing material. Consideration must also be given to the degree of evaporation toward dryness of the sample in making the idealized weight calculations.

Other variables which must be taken into consideration when making calculations of a given type of strand are glass density, strand traversal path, and type of size applied. Additional factors which must be considered in the calculation of the idealized strand in order to permit an accurate adjustment for the desired diameter of the filament include speed of collection, shape and size of the collection sample, temperature of the melt and the rate of yardage modification with temperature changes. In view of the foregoing, it is apparent that the number of variables involved in making weight calculations for a given sample of strand of filaments of desired diameter present some difficulty to the extent that diameter control by such observation of actual weight in comparison against a calculated weight can only be accomplished by experiences and skilled personnel. In spite of this difiiculty, however, the weight observation and calculation method is still more accurate and economical than known available optical, mechanical, or electrical test instruments.

In view of the foregoing, it is a principal object of the present invention to provide an improved method and Patented Nov. 16, 1965 means for regulating the diameter of continuous filaments during their production by enhancing the features of the weighed sample technique and at the same time reducing the complexity of such technique to the extent that even the most unskilled of personnel can make corrective adjustments to consistently produce the desired product.

A more specific object of the invention is to provide a method and means for controlling the diameter of continuous filaments during production which method is more economical in material and in the need for labor.

Still another object of the invention is to provide a weighed sample technique for regulating the dimension of filaments during production which is adapted to utilization of size samples which will cover up short term cyclic yardage variations and yet provide an accuracy within a tolerance range of :l.0%.

A still further object of the invention lies in providing a method for regulating the dimension of filaments collected into a strand which reduces the need for frequent calibration and by which obvious errors are easy to detect.

In brief these objects are obtained according to the present invention by means which provide a simple and direct indication of the corrective adjustment necessary to produce filaments of desired dimension involving no more than the mere physical and mental steps confronted in weighting a sample production quantity. To accomplish this end, the variable adjusted to establish the desired filament diameter is the temperature of the molten supply. By raising the temperature of the supply as filaments are being attenuated therefrom at a fixed velocity, the diameter dimension of the filaments is increased, while upon lowering the temperature of the supply, the diameter dimension is decreased. In the glass fiber-forming industry, the more common terminology referring to the diameter dimension of continuous fibers is yardage per pound. Yardage per pound increases as the temperature of the supply is decreased and correspondingly diminishes as the temperature is increased. Thus, by obtaining the weight of the strands collected at a constant velocity over a measured period of collection time, the diameter of the filaments can be calculated.

According to the present invention, however, the weighing mechanism is arranged to convert yardage or diameter measurements to temperature adjustments necessary to correct deviations from desired dimension of filaments being produced. To accomplish this result, a family of nomographic temperature scales is associated with the moveable index needle of a weighing mechanism to translate weight measurements directly into temperature adjustment indications, thus eliminating the need for complex calculation of yardage per pound as well as the temperature adjustments necessary to attain desired dimensional values. A still further simplification of the family of nomographic scales is made possible when time 'is constant for collection of all samples which permits reduction of the family of scales to but a single scale.

A principal feature of the invention lies in the fact that anyone who can make a weight measurement can be taught in a matter of minutes how to make adjustments of fiber-forming equipment to obtain the desired diameter of filaments in strands being produced. Correspondingly, the cost of labor for maintaining quality production from given fiber-forming apparatus is greatly reduced, both by way of skills required and time consumed in making adjustments for desired dimensional output.

Another feature of the invention lies in the simplicity and the adaptability of the invention to conventional fiber-forming apparatus, thus eliminating the need for complex equipment and making the arrangement readily available in existing production facilities.

A still further feature of the invention lies in the greatly improved quality obtainable by use of the invention with a minimum of added cost as well as a reduction in the need for skills in attaining consistency, uniformity and a low tolerance specification in products produced.

Other objects and features which I believe to be char acteristic of my invention are set forth with particularity in the appended claims. My invention, however, both in organization and manner of construction, together with further objects and advantages thereof may be best understood by reference to the following description taken in connection with the accompanying drawings in which:

FIGURE 1 is a somewhat schematic side-elevational view of apparatus of the present invention for producing low tolerance, uniform diameter glass filament strands;

FIGURE 2 is a perspective view of balance unit for translating the product measurement into temperature adjustments in the arrangement of FIGURE 1;

FIGURE 3 is an illustration of a nomographic family of indicia adapted to installation in weight balancing units such as the type shown in FIGURE 2;

FIGURE 4 illustrates another tomographic chart arrangement adapted to installation in the balance unit of FIGURE 2 arranged to provide direct indication of need for temperature adjustments in the fiber producing equipment of FIGURE 1; and

FIGURE 5 is an illustration of a basic family of curves providing information from which the nomographic charts of FIGURES 3 and 4 can be developed.

Referring to the drawings in greater detail, FIGURE 1 illustrates an arrangement of apparatus for the production of continuous glass fibers including an electrically heated feeder associated with a supply of glass fed from a source such as the forehearth 13 of a melting tank, shown in dotted lines. The molten glass flows in the form of streams from orifices in the bottom of the feeder 10 and is attenuated into individual filaments 11 which are then gathered at a gathering shoe 12 to which sizing or binder fluid is supplied from a feeding tube 14 for application to the filaments. The temperature and viscosity of the material flowing from the feeder is determined by the flow of electric current through the feeder which is in a sense a resistance heater. The filaments 11 are drawn together at the shoe 12 in the form of a strand 16 which is collected into a package 22 on a collection tube 23. The tube 23 in turn is mounted on a collet 21 of a winder which supplies the forces extending upwardly through the filaments 11 to effect the attenuation of the streams fed from the feeder 10. A traverse member 18, such as a spiral wire type traverse conventional in the glass fiber-forming industry, moves the strand back and forth across the width of the collection tube 23 to build up a package of desired configuration adapted to being handled without likelihood of sloughing. A timer unit 19 associated with the winder 20 provides means by which the length of the collection period can be set to an exact predetermined length of time, while an indicator dial 25 associated with the timer provides a check by indicating the actual period of collection of the material in the package 22.

A strand pushoff or holdoff arm 17 of the winder operates in association with the timer 19 to hold the strand at the edge of the collection tube 23 at the beginning of the package collection cycle until the timer releases the holdoff mechanism to actually start the strand in the package proper. At the end of the preselected time for collection of the package 22, as set at the timer 19, the strand holdoff mechanism pushes the strand back to the edge of the package, thus assuring that the package itself is wound during only the exact time determined by the setting of the timer 19. The

4- small excess of material collected at the edge of the package at the beginning and end of the packaging cycle is then cut from the tube 23 prior to measurement of the package to assure that only the material of the main body of the package is present for measurement.

The diameter of the filaments 11 is determined by the rate of attenuation of the fibers from the streams supplied from the feeder 10 as well as by the temperature of the feeder 10 which regulates the viscosity of the molten glass flowing therefrom, and correspondingly the rate of supply of the material from the feeder. When the rate of attenuation is a fixed value as in most conventional fiber-forming operations, the diameter of the filament is then determined by the temperature of the feeder 10. When the feeder temperature is too high, the viscosity of the fluid flowing therefrom is low and the diameter of the filaments produced is correspondingly larger than desired. In corollary relation, when the temperature of the feeder is too low, the viscosity of the material flowing therefrom is too high and the diameter of the filaments produced is less than desired. At the extremes of the fiberization temperature range, fibers cannot be produced since the molten material either will fiow as droplets when the temperature is too high or the material will be ruptured when the temperature is too low. Within these extremes, however, fibers of exacting uniformity in diameter dimension can be produced when the viscosity of the emitted material is established and maintained uniform within a small tolerable range of temperature.

By way of example, the tolerable range of temperature for the usual feeder in order to produce filaments having a diameter dimension within a tolerance range of i1.0% may be in the order of :2" F. in the temperature range of from 2,300 to 2,600 F.

In order to maintain the resistance heated feeder at a predetermined temperature for desired filament diameter, the flow of electric current to the feeder over the lines L] and L2 is regulated by a variable impedance unit 26 such as a saturable core reactor which imposes more impedance to the feeder circuit when the temperature of the feeder is on the high side, and reduces its value when the temperature of the feeder is low. The variation in impedance is accomplished through a temperature regulating control unit 25 such as a Wheelco or a Minneapolis- Honeywell temperature control unit. The temperature of the feeder 10 is sensed by a thermocouple 24 connected to the temperature control unit 25 which is adjusted by Way of its selector knob 28 for the desired temperature above and below which variation signals are supplied for adjustment of the current regulating variable impedance unit 26.

The control unit 25 indicates the temperature at a scale 27 and supplies signals to the saturable core-type unit 26 to vary its impedance value in the main power circuit to thefeeder 1t), dependent upon deviation of the actual temperature of the feeder from the desired value set by adjusting the preselection knob 28 for such temperature. A fine adjustment means in the form of a knob 29 is also provided in the control unit 25 for us whenever actual yardage or diameter measurements of the filaments indicate that the temperature at which the automatic equipment is set is either too high or too low for the product desired.

The temperature at which the feeder is to be maintained is selected by setting an indicator needle 38 on the tem-- perature scale 27 of the unit 25 by way of the adjustment knob 28. The actual temperature of the feeder is then sensed by the thermocouple 24 which supplies a corresponding electrical signal to the control unit 25 which in turn provides an indication of the actual measured temperature by way of the temperature indicating needle 37. The unit 25 matches the actual measured temperature against the preselected temperature value. indicated by the needle 38, and any deviations between the actual and, preselected temperature results in the unit 25 providing an electrical signal to the variable impedance component 26 to increase or reduce the current flow in the feeder until the preselected temperature indicated by the needle 38 is established at the feeder 10. Since inaccuracies in circuit component values and in fiber forming conditions can occur during use, the fine adjustment by way of the knob 29 is provided to permit adjustment for an exact value in a narrow range of a few degrees within the broader range of say for example 2,000 to 3,000 F.

Experience indicates that even though a fiber producing arrangement or position can be set initially for production of fibers exactly within specification, the system for extraneous reasons can vary gradually especially over longer periods of continuous operation to the extent that filaments produced may be out of tolerance. Accordingly, periodic check must be made of the fibers being produced by a given operating assembly to assure that the diameter of filaments and the strand properties are within the allowable tolerance range. When filament dimensions are outside of specified value, then calculation methods or other means must be resorted to to determine what adjustment should be made in temperature at the feeder to re-establish the desired product output.

According to the present invention, the check of product dimensions is made by placing samples of the output of the respective fiber-producing position on a balance scale and in the physical steps involved in weighing the samples, to automatically convert the balancing operation into a temperature adjustment indication. FIGURE 2 illustrates a balance scale 30 having two balance pans 31 and 32 for balancing weights in one against the collected sample in the other. A needle 36 for the balance scale indicates the relative weight relationship between the objects placed upon the two balance pans 31 and 32, while a nomographic chart 35 across which the needle 36 sweeps, is according to the present invention arranged to provide indication as to whether any adjustment in the feeder temperature is necessary and the magnitude of such adjustment should correction be required to eliminate deviations from a desired diameter in the filaments of the strand product.

In the fibrous glass industry, the diameter of continuous filaments in a strand is practically synonymous with figures representing strand yardage per pound. For example, 150s strands (15,000 yds./lb.) made up of 204 continuous filaments have a commercial tolerable diameter range of from .0000350 to .0000399 while 225s (22,500 yds./lb.) have a range of .0000250 to .0000299. Thus, when the diameter of the filaments is too large, the yardage per pound must be increased. In another sense, if the rate of attenuation is fixed as in the usual case, a pound of glass in strand form having filaments larger in diameter than desired will not have as great a length as strand falling within the specification. In still another sense, a pound of glass fibers will be attenuated within a shorter period of time if the diameter of the filaments is too large in comparison to the time required to attenuate a pound should the diameter of the filaments be within specification. Thus, weight of the strand product attenuated over a given length of time is representative of the average diameter of the filaments in the strand.

With such information on hand, a family of curves can be made such as illustrated in FIGURE 5 wherein the abscissa of the chart represents time for collection of a sample and the ordinate is in either weight of the collected product or in yards per pound. Each time for collection of a given type of strand having a pre-established number of filaments of desired diameter will provide correspond ing predeterminable value in weight as well as in yards per pound.

With calculated data available relative to the yardage per pound for each value in the range of time within which samples are to be collected, a curve can be drawn corresponding to the exact feeder temperature which will provide the desired diameter of filaments in a sample strand. Rather than forming a single graphic line, however, a zero band is preferred between Zero lines located on each side of the tolerable range of feeder temperature which will provide fibers within, for example 1.0% of the desired diameter. Thus, readings falling within the band between the two zero lines would indicate that the product samples is within tolerance. Temperature adjustment curves, such as 5 and 10 F. steps above and below the zero lines can be provided as in FIGURE 5 to indicate the amount of adjustment necessary when a measured sample falls outside of the zero band. Such data is calculable based upon tests of yardage change experienced with variations in feeder temperature in proximity to the temperature which will provide the desired filament diameters.

Thus, when the time for collection of a sample being measured is known, an actual weight measurement of the sample can be used to determine from the family of curves in FIGURE 5 Whether the temperature of the feeder is too high or too low and what magnitude of adjustment is necessary. In utilizing a chart such as that of FIGURE 5, however, requires manual or visual intersection of the abscissa or ordinate value for the measured sample in order to obtain a point in the family of curves which will indicate if any adjustment is necessary to produce the fibers of desired dimension.

According to the present invention, however, the manual intersection of abscissa and ordinate values in the family of curves is eliminated. This is accomplished by use of the indicator needle in conjunction with a nomographic representation of the variable factors directly on the face chart of the weighing scale. The needle of the weighing scale sweeps across the nomographic chart of the type shown in FIGURE 3 and comes to rest at a value determined by the sample, and in knowing the time over which such sample was collected, the corresponding time line of the nomograph can be read directly at the needle for the adjustment in feeder temperature necessary, if any, to provide the filaments of diameter and yardage desired.

Formulas about which the nomographic scale charts of FIGURES 3 and 4 are developed are as follows:

(Collection time) (Avg. pull speed) Yards/pounds: (Net sample weight) (Glass content) Percent glass content 100 (Mosture Binder contents) Average pull speed for sample (Speed at start) I(Speed at end) 2 Temperature adjustment in F Measured yd./l'b. desired yd./lb. yd./lb./ F. where yd./lb./ F. is pre-evaluated by test for products produced.

Example.-For s strand (15,000 yd./lb.) the chart of temperature relation may be arranged as follows:

Thus, in the above illustration, the tolerable range between the and zero index marks is :150 yards or +10% outside of which the amount of corrective adjustment required is indicated.

One factor which makes the nomographic reading of temperature adjustment possible is the finding that actual yardage or diameter of the filaments can be read directly in spite of the presence of moisture and binder in addition to the glass of the strand if the collection is made over an appreciable period to eliminate short term variation and if the reading is made within a sort period of time, such as thirty minutes, after collection. In spite of the fact that moisture content, binder application speed, package build, traverse type, package size, drying time, drying temperature, and air movement all have an infiuence on Weight of samples, tests indicate that moisture gain remains fairly uniform and will vary only about plus or minus .05% from the average moisture gain for a particular forming product if measurements are made within thirty minutes of formation and collection. Thus, calculation can be made of yardage and fiber diameter for glass alone with but a small statistical deviation from actual values. In other words, zero compensation can be provided for the sample being measured including moisture, binder, and glass content in the balance weight placed on the balance 31 in addition to the tube tare weight once actual time of collection is known. The charts of this invention are designed so that over the range of time covered by the chart, the zero compensate value is fixed and the chart itself compensates for the different quantities of moisture and binder present for the different time periods of the chart during which the samples are collected.

Previous to the present invention, samples taken over such a period of time were required to have their binder dried and solids material burned off before the actual Weighing of the glass. By the present arrangement, however, such excess handling and test of the glass is eliminated since statistically the moisture content is consistent if the sample is collected over a sufficiently long period of time. Therefore, to provide even greater accuracy, it has been found that full packages of the strand are more desirable for measurement of strand dimensions. Since the full package samples are measured without destruction of the sample, the waste produced by the previous skein method, wherein shorter quantities were measured and then thrown away, is eliminated.

The chart 35 shown in FIGURE 3 represents values of yardage or weight of samples such as 150s strand (15,000 yds./lbs.) collected in periods of from 360 to 480 seconds and indicates temperature adjustments considering the presence of moisture and binder in the sample. The zero compensate weight is a fixed value for this chart equivalent to that which will place the weight needle in the center of the zero band when a sample being measured is within yardage specification and is collected within a period for which the nomographic chart was formed considering the presence of moisture and binder solids. By way of example, the balance needle is represented by a dotted line ex tending generally vertically across the first family of nomographic values of the chart. If the time for collection of the sample were 400 seconds, then the dotted line representation of the needle in falling between the two zero lines indicates that the sample is in proper dimension. If, however, the time for collection were 410 seconds, then the needle points out on the nomographic chart that an adjustment of plus 2 degrees F. is necessary at the feeder to provide a product within specifications.

The dotted line extension of the first field of values 41 of the nomographic illustrates how the chart can be broken up into two pieces since the dotted line portion 42a in the chart 35 has been lifted to provide a second field 42 in side-by-side position with the first field 41 in order to make a reading of the full scale easier in a wider, but shorter, viewing area.

Carrying the invention one step further toward simplification, by selecting a fixed time for collection of packages of strand for all operating positions so that every package produced from a bank of forming positions is collected over exactly the same time, the nomographic chart for measuring the product output of the bank can be reduc d to a single line. Such simplification is illustrated by the chart in FIGURE 4 wherein the family of lines representing times in FIGURE 3 are reduced to a single line for each product likely to be produced in a bank of forming positions. The chart 45 in FIGURE 4 shows a single t p line 51 representing adjustments to be made for l50s strand (15,000 yards per pound) where the full package is collected over a period, for example, of exactly 20 minutes. The second line 52 is a scale indicating the adjustments necessary for correcting the operating temperature of a position producing s strands (13,500 yards per pound), while the scale 53 indicates adjustments necessary for full packages of 225s strands (22,500 yards per pound). The gram weight statements at the lift of each scale indicate the value of the zero compensate weight necessary for each type of strand. Thus, by knowing the type of product produced from a position collecting strands over an exact given time for which the scales are made, the actual measurement of the sample can be read in temperature adjustment necessary, rather than reading the sample measurement in weight, thus eliminating the curnbersome calculations otherwise entailed in determining such information.

In view of the foregoing, it will be understood that while I have shown certain particular forms of my invention, I do not wish to be limited thereto since many modifications may be made within the concept of the invention. For example, the nomographic chart may be provided with indications of values calibrated into other measuring systems such as the c.g.s. system and the balance mechanism can be an unbalanced scale having compensating weights already built therein. In this respect, tare weight of the collection tubes can be marked on each tube, or the tubes can all be of the same weight to make tare weight a constant which can be incorporated into the scale. Correspondingly moisture content in packages of definite siz can also be incorporated into the balance system. I, therefore, contemplate by the appended claims to cover all modifications that fall within the true spirit and scope of my invention.

I claim:

1. The method of establishing the temperature necessary for a molten supply of material to form by constant attenuation therefrom a continuous fiber of desired diameter comprising collecting a sample of such fiber attenuated at a relatively fixed velocity over a measured period of time, weighing said sample, associating with the Weight indicated needle of the weighing scale a nomographic chart of temperature as related to weight for the time of collection of samples of such continuous fiber by providing a family of temperature adjustment scales in intersecting relation with a family of scales of times of collection for such samples such that for each time of collection of a sample within the range of said time scales the needle will provide an indication of temperature adjustment necessary to produce fibers of desired diameter, obtaining from the needle indication on such nomographic chart the value of adjustment in temperature necessary to produce a continuous fiber having an average diameter corresponding to that desired, and then making an adjustment in temperature of said molten material corresponding to the value thus obtained from the needle indication.

2. In the production of continuous fibers of heat-soft ened material such as molten glass wherein continuous fibers are attenuated at a predetermined velocity from streams flowing from a molten mass of the material, the method of establishing the temperature of the molten mass necessary to produce fibers of desired diameter Without complex calculation comprising plotting for fibers of desired diameter a family of time scales on the face of a weighing scale having a weight indicating needle moveable across its face, each of said family of time scales representing time for collection of a sample of said fiber, plotting a family of temperature adjustment scales in intersecting relation with said time scales, both said families being plotted in transverse relation with respect to the range of positions of the indicator needle of such weighing scales, orientation of said families of scales to each other and each position of said needle being based upon timetemperature relationships for formation of fibers from said molten material such that for each time of collection of samples weighed the needle will provide an indication of the adjustment of temperature of the molten source necessary to produce the fibers of the desired diameter, collecting a fiber sample attenuated at said predetermined velocity over a measured period of time within the time range of the family of time scales on said face, placing said sample on said weighing scale and reading at the needle and on the time scale corresponding to the measured time period for the sample, the magnitude of adjustment in temperature of the molten mass necessary to produce fibers of said desired diameter, and then making an adjustment in the temperature of said molten mass corresponding to the magnitude read at the needle to thereby establish the temperature necessary to produce such fibers.

3. In the production of continuous fibers of heat-softened material such as molten glass wherein continuous fibers are attenuated at a predetermined velocity from streams flowing from a molten mass of the material, the method of establishing the magnitude of adjustment in temperature of the molten mass necessary to produce fibers of desired diameter without complex calculation comprising plotting for fibers of desired diameter a temperature adjustment chart for said molten mass corresponding to a given time for collection of a sample of said fiber such that for each position of the needle of said weighing scale an indication is provided of the adjustment of temperature of the molten source necessary to produce fibers of desired diameter, collecting a fiber sample attenuated at a predetermined velocity for said given time, placing said sample of said Weighing scale and reading at the needle the magnitude of adjustment in temperature of the molten mass necessary to produce fibers of said desired diameter, and then making an adjustment in temperature of said molten mass corresponding to the magnitude read at the needle to thereby establish the temperature necessary to produce fibers of desired diameter.

4. In the production of continuous fibers of heat-softenable material such as molten glass wherein continuous fibers are attenuated at a predetermined velocity from streams flowing from a molten mass of the material, the method of establishing from collected samples of fibers the temperature of the molten material necessary to produce fibers of desired diameter comprising providing a chart for the indicating face of a weighing scale including for fibers of desired diameter, a scale of a range of time within which samples are to be collected, providing also on said chart a scale of magnitude of temperature adjustment necessary to obtain fibers of desired diameter for samples collected over measured periods within said range of time, said chart scales being provided in transverse relation with respect to the range of positions of the indicator needle of such weighing scale such that for each time of collection of samples weighed, the needle will provide an indication of the adjustment in temperature of the molten material necessary to produce the fiber of desired diameter, collecting a sample of such fiber over a period of time within the range of the time on said time scale, placing said sample upon said Weighing scale, reading at the needle on the scale corresponding to the time for collection of the sample the magnitude of adjustment of the temperature of the molten material necessary to produce fibers of desired diameter, and then making an adjustment in temperature of said molten material corresponding to the value thus obtained from the needle indication.

References Cited by the Examiner UNITED STATES PATENTS 1,884,320 10/1932 Smith 17743 2,306,789 12/ 1942 McNamara 65-29 2,844,028 7/1958 Benn 73-160 3,013,095 12/1961 Russell 65162 DONALL H. SYLVESTER, Primary Examiner.

WILLIAM B. KNIGHT, Examiner. 

3. IN THE PRODUCTION OF CONTINUOUS FIBERS OF HEAT-SOFTENED MATERIAL SUCH AS MOLTEN GLASS WHEREIN CONTINUOUS FIBERS ARE ATTENUATED AT A PREDETERMINED VELOCITY FROM STREAMS FLOWING FROM A MOLTEN MASS OF THE MATERIAL, THE METHOD OF ESTABLISHING THE MAGNITUDE OF ADJUSTMENT IN TEMPERATURE OF THE MOLTEN MASS NECESSARY TO PRODUCE FIBERS OF DESIRED DIAMETER WITHOUT COMPLEX CALCULATION COMPRISING PLOTTING FOR FIBERS OF DESIRED DIAMETER A TEMPERATURE ADJUSTEMENT CHART FOR SAID MOLTEN MASS CORRESPONDING TO A GIVEN TIME FOR COLLECTION OF A SAMPLE OF SAID FIBER SUCH THAT FOR EACH POSITION OF THE NEEDLE OF SAID WEIGHING SCALE AN INDICATION IS PROVIDED OF THE ADJUCTMENT OF TEMPERATURE OF THE MOLTEN SOURCE NECESSARY TO PRODUCE FIBERS OF DESIRED DIAMETER, COLLECTING A FIBER SAMPLE ATTENUATED AT A PREDETERMINED VELOCITY FOR SAID GIVEN TIME, PLACING SAID SAMPLE OF SAID WEIGHING SCALE AND READING AT THE NEEDLE THE MAGNITUDE OF ADJUSTMENT IN TEMPERATURE OF THE MOLTEN MASS NECESSARY TO PRRDUCE FIBERS OF SAID DESIRED DIAMETER, AND THEN MAKING AN ADJUSTMENT IN TEMPERATURE OF SAID MOLTEN MASS CORRESPONDING TO THE MAGNITUDE READ AT THE NEEDLE TO THEREBY ESTABLISH THE TEMPERATURE NECESSARY TO PRODUCE FIBERS OF DESIRED DIAMETER. 